RandR 1.2 support in X.org
The X.org shipped in Mandriva Linux 2008 contains support for version 1.2 of the RandR protocol, which handles dynamic changes in the configuration of attached monitors. This version is a major improvement from the previous 1.1 version, with new features including dynamic detection of attached monitors (so X.org knows when you plug in or unplug a monitor, when RandR 1.2 is in use). Only a few drivers support the RandR 1.2 protocol: the intel driver for Intel 810 and later graphics adapters, the ati_6.7 version of the ati driver for ATI graphics cards (see above for details on the two versions of this driver included in Mandriva Linux 2008), and the nv open source driver for NVIDIA graphics cards (which includes RandR 1.2 support only for GeForce 8xxx series cards).
Mandriva has written and included an improved version of the krandr KDE panel applet, which supports the RandR 1.2 protocol. If you are using one of the drivers which supports the RandR 1.2 protocol, you should find that you can use this applet to control the layout of dual-screen setups, and to configure newly plugged in monitors without restarting X. If your driver only supports the older RandR 1.1 protocol, the more restricted features you are used to will still be available.
Maybe this has something to do with your success with you setup. I'm going to bow out of this topic for a while, so good luck with your issues. I would look into this a little more on google and see what this is saying and maybe you can get it applied in Ultimate Edition or Ubuntu.